SPI library usage in Arduino - Mini Project: Build & Apply

SPI Library Usage in Arduino

📖 Scenario: You are building a simple Arduino project that communicates with an SPI device, like a sensor or display. SPI (Serial Peripheral Interface) is a way for your Arduino to talk to other devices quickly using a few wires.In this project, you will learn how to set up SPI communication using the Arduino SPI library, send data to the SPI device, and read data back.

🎯 Goal: Build a simple Arduino program that initializes SPI communication, sends a byte of data to an SPI device, and reads a byte back.

📋 What You'll Learn

Use the Arduino SPI library

Initialize SPI communication with SPI.begin()

Set SPI settings with SPISettings

Send data using SPI.transfer()

Read data returned from SPI.transfer()

Use a chip select pin to control the SPI device

💡 Why This Matters

🌍 Real World

SPI is used in many electronics projects to connect microcontrollers to sensors, displays, memory chips, and other devices quickly and efficiently.

💼 Career

Understanding SPI communication is important for embedded systems engineers, hardware developers, and anyone working with microcontrollers and electronics.

1

Setup SPI and Chip Select Pin

Create a variable called chipSelectPin and set it to 10. In the setup() function, set chipSelectPin as an output and set it HIGH. Then call SPI.begin() to start SPI communication.

Arduino

int chipSelectPin = 10;

void setup() {
  pinMode(chipSelectPin, OUTPUT);
  digitalWrite(chipSelectPin, HIGH);
  SPI.begin();
  // Your code here
}

void loop() {
  // Your code here
}

Hint

Remember to set the chip select pin as output and set it HIGH before starting SPI.

2

Configure SPI Settings

Create a variable called spiSettings using SPISettings with a clock speed of 4000000 (4 MHz), data order MSBFIRST, and SPI mode SPI_MODE0.

Arduino

int chipSelectPin = 10;

SPISettings spiSettings(4000000, MSBFIRST, SPI_MODE0);

void setup() {
  pinMode(chipSelectPin, OUTPUT);
  digitalWrite(chipSelectPin, HIGH);
  SPI.begin();
  // Your code here
}

void loop() {
  // Your code here
}

Hint

Use SPISettings with the exact parameters: 4000000, MSBFIRST, SPI_MODE0.

3

Send and Receive Data Using SPI.transfer()

In the loop() function, use SPI.beginTransaction(spiSettings) to start SPI communication. Then set chipSelectPin LOW to select the device. Send the byte 0x42 using SPI.transfer() and store the returned byte in a variable called receivedData. Set chipSelectPin HIGH to deselect the device. Finally, call SPI.endTransaction().

Arduino

int chipSelectPin = 10;

SPISettings spiSettings(4000000, MSBFIRST, SPI_MODE0);

void setup() {
  pinMode(chipSelectPin, OUTPUT);
  digitalWrite(chipSelectPin, HIGH);
  SPI.begin();
}

void loop() {
  SPI.beginTransaction(spiSettings);
  digitalWrite(chipSelectPin, LOW);
  byte receivedData = SPI.transfer(0x42);
  digitalWrite(chipSelectPin, HIGH);
  SPI.endTransaction();
  // Your code here
}

Hint

Use SPI.beginTransaction and SPI.endTransaction around your SPI transfer. Remember to control the chip select pin.

4

Print the Received Data

Add Serial.begin(9600) in the setup() function to start serial communication. In the loop() function, after receiving data, print the text "Received: " followed by the value of receivedData using Serial.println(). Add a delay of 1000 milliseconds at the end of loop().

Arduino

int chipSelectPin = 10;

SPISettings spiSettings(4000000, MSBFIRST, SPI_MODE0);

void setup() {
  pinMode(chipSelectPin, OUTPUT);
  digitalWrite(chipSelectPin, HIGH);
  SPI.begin();
  Serial.begin(9600);
  // Your code here
}

void loop() {
  SPI.beginTransaction(spiSettings);
  digitalWrite(chipSelectPin, LOW);
  byte receivedData = SPI.transfer(0x42);
  digitalWrite(chipSelectPin, HIGH);
  SPI.endTransaction();
  Serial.print("Received: ");
  Serial.println(receivedData);
  delay(1000);
  // Your code here
}

Hint

Use Serial.begin(9600) in setup() and print the received data with Serial.print and Serial.println.